#include <sys/socket.h>
#include <pthread.h>
#include <iostream>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
using namespace std;
#define BUF_SIZE 100
#define MAX_CLNT 256

void *handle_clnt(void *arg);
void send_msg(char *msg, int len);
int clnt_cnt = 0;
int clnt_socks[MAX_CLNT];
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

int main(int argc, char **argv)
{
    int serv_sock, clnt_sock;
    struct sockaddr_in serv_adr, clnt_adr;
    socklen_t clnt_adr_sz;
    pthread_t t_id;
    if (argc != 2)
    {
        printf("Usage : %s <port>\n", argv[0]);
        exit(1);
    }
    serv_sock = socket(AF_INET, SOCK_STREAM, 0);
    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_port = htons(atoi(argv[1]));
    bind(serv_sock, (sockaddr *)&serv_adr, sizeof(serv_adr));
    listen(serv_sock, 5);
    while (1)
    {
        clnt_adr_sz = sizeof(clnt_adr);
        clnt_sock = accept(serv_sock, (sockaddr *)&clnt_adr, &clnt_adr_sz);
        pthread_mutex_lock(&mutex);
        clnt_socks[clnt_cnt++] = clnt_sock;
        pthread_mutex_unlock(&mutex);
        pthread_create(&t_id, nullptr, handle_clnt, (void *)&clnt_sock);
        pthread_detach(t_id);
        printf("Connected client IP: %s \n", inet_ntoa(clnt_adr.sin_addr));
    }
    close(serv_sock);
    return 0;
}

void *handle_clnt(void *arg)
{
    int clnt_sock = *((int *)arg);
    int str_len = 0, i;
    char msg[BUF_SIZE];
    while ((str_len = read(clnt_sock, msg, BUF_SIZE)) != 0)
    {
        send_msg(msg, str_len);
    }
    for (i = 0; i < clnt_cnt; i++)
    {
        if (clnt_sock == clnt_socks[i])
        {
            while (i < clnt_cnt - 1)
            {
                clnt_socks[i] = clnt_socks[i + 1];
                i++;
            }
            break;
        }
    }
    clnt_cnt--;
    pthread_mutex_unlock(&mutex);
    close(clnt_sock);
    return nullptr;
}
void send_msg(const char *msg, int len)
{
    int i;
    pthread_mutex_lock(&mutex);
    for (i = 0; i < clnt_cnt; i++)
    {
        write(clnt_socks[i], msg, len);
    }
    pthread_mutex_unlock(&mutex);
}